The following aspects of lipid metabolism as it relates to the problem of ketosis in ruminants will be studied: 1. The role of insulin in the development of ketosis is being studied by measurement of insulin levels and specific blood metabolites in normal vs. ketosisprone cows before and after parturition. The effects of alloxan diabetes in goats is being studied in relation to its effects on ketogenesis and esterification in the liver to determine whether these occur simultaneously. Effects of lack of insulin on acetate metabolism are also being studied. 2. Attempts are being made to develop fatty livers in ruminants to study the factors responsible and their relationship to ketosis. Preliminary attempts to produce fatty livers with orotic acid or isopropanol have been unsuccessful. Current attempts will involve underfeeding combined with a glucose drain supplied by lactation, pregnancy, or phlorizin. Preliminary results suggest success with these procedures. 3. Attempts will be made to clarify the mechanism by which administration of nicotinic acid benefits the ketotic cow, as has been shown in previous work by this group. Effects on adipose lipolysis have shown an initial inhibition followed by a rebound to above pre-treatment levels. Other effects than those related to lipolysis are being studied. These include effects on hepatic ketogenesis, triglyceride release rate from the liver, carbohydrate metabolism as measured by glucose tolerance, and on hormone secretion.